ARS | Publication request: Altering plant secondry metabolism to achieve broad spectrum insect control and reduce mycotoxins

Submitted to: Book Chapter
Publication Type: Book/Chapter
Publication Acceptance Date: February 12, 2008
Publication Date: N/A

Technical Abstract: Mycotoxins are toxic or carcinogenic compounds produced by fungi, including Aspergillus and Fusarium molds that colonize seeds of maize, cotton, peanuts, or tree nuts. Insect herbivores of plant tissue often enhance mold infection. Transgenic maize expressing the Bacillus thuringiensis (Bt) toxin produce ears with lower mycotoxin levels when the target insect pest is effectively controlled. However, Bt toxins are generally species specific; and therefore, new transgenic strategies for broad insect control need to be developed. The vast diversity of plant secondary biochemicals reflects the strategy of non-motile plants to defend themselves from pathogens and animal herbivores. Research in recent years revealed that many of these plant biochemicals are synthesized by a number of enzymes that are coordinately regulated at the gene level by transcription factors. Altering the expression of these transcription factors by genetic engineering opens the possibility that these secondary biochemicals may be synthesized in specific tissues to combat insect herbivores and reduce mycotoxin contamination. Alternatively, well-studied secondary biochemical pathways may be modified or transferred from one plant species to another and tested for effective insect resistance. Transgenic manipulation of secondary metabolism must be carefully considered because redirection of plant energy reserves may hinder plant yield. The advent of genetic engineering and advances in plant biochemistry has opened up the exciting possibilities of utilizing the diversity of secondary biochemicals for protecting valuable crop commodities.